(1) Field of the Invention
The present invention relates to a double sash or window structure comprising a window frame for a first sash disposed on the outdoor side and a window frame for a second sash disposed on the indoor side.
(2) Brief Description of the Prior Art
Double sash structures comprising a window frame for a first sash disposed on the outdoor side, a window frame for a second sash disposed on the indoor side and a heat-insulating material interposed between the two window frames are known. In conventional double sash structures having the above-mentioned structure, connecting portions are formed on connecting ends of both frames and these portions are combined together through an intermediate heat-insulating member. Accordingly, the assembling and attaching operations are very troublesome.
Since the window frames and frames of screens are ordinarily formed of metallic materials in conventional double sash structures, the heat of warmed air in the room escapes to the outside through the window frames and screens and cold air outside the room cools air in the room through the window frames and screens. Accordingly, the intended effects of the double sash structure cannot be attained sufficiently. Moreover, condensed water dews are generated because window frames on the indoor side are cooled, and the interior of the room is readily contaminated with these condensed water dews. These are defects involved in the conventional double sash structures.